docs: def set_nweights(self, nweights):
          r"""
          Set multiple n-weights / edge-weights.
          
          Parameters
          ----------
          nweights : dict
              A dictionary with (node-id, node-id) tuples as keys and (weight-a-to-b, weight-b-to-a) as values.
          
          Notes
          -----
          The object does not check if the number of supplied edges in total exceeds
          the number passed to the init-method. If this is the case, the underlying
          C++ implementation will double the memory, which is very inefficient.
                
          See `set_nweight` for raised errors.
          """
          for edge, weight in list(nweights.items()):
              self.set_nweight(edge[0], edge[1], weight[0], weight[1])